Q&A - P5 Math
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On Mon, M read 52 pages of a book. On Tues, he read 2/5 of the remaining pages. If he still had 1/3 of the book left to be read, how many pages were there in the book?
I am unable to draw the model here but it goes like this:
52 pages (Mon) + 2/5 (Tues) + 3/5 (unread)
So 1/3 = 3/5 unread
Hence 2/3 = 52 pages + 2/5 read
I get common denominator of 15, hence
10/15 = 52 pages + 6/15, so
4u => 52 pages
15u=> 195 pages but answer is 117 pages where becos 1/3 = 3/5 unread, 2/3 must be = 6/5 read
Hence 52 pages = 4/5 read
9u => 117 pages
Why is that so? -
Superbugs:
On Mon, M read 52 pages of a book. On Tues, he read 2/5 of the remaining pages. If he still had 1/3 of the book left to be read, how many pages were there in the book?
I am unable to draw the model here but it goes like this:
52 pages (Mon) + 2/5 (Tues) + 3/5 (unread)
So 1/3 = 3/5 unread
Hence 2/3 = 52 pages + 2/5 read
Should be 2/3 of the book = 52 pages + 2/5 of remaining pages.
Hence we cannot subtract the 2 fractions
10/15 = 52 pages + 6/15, so
4u => 52 pages
15u=> 195 pages but answer is 117 pages where becos 1/3 = 3/5 unread, 2/3 must be = 6/5 read
Hence 52 pages = 4/5 read
9u => 117 pages
Why is that so? -
Superbugs:
HiOn Mon, M read 52 pages of a book. On Tues, he read 2/5 of the remaining pages. If he still had 1/3 of the book left to be read, how many pages were there in the book?
I am unable to draw the model here but it goes like this:
52 pages (Mon) + 2/5 (Tues) + 3/5 (unread)
So 1/3 = 3/5 unread
Hence 2/3 = 52 pages + 2/5 read
I get common denominator of 15, hence
10/15 = 52 pages + 6/15, so
4u => 52 pages
15u=> 195 pages but answer is 117 pages where becos 1/3 = 3/5 unread, 2/3 must be = 6/5 read
Hence 52 pages = 4/5 read
9u => 117 pages
Why is that so?
the MD approach ...![](\"http://i56.tinypic.com/xeig7d.jpg\")
http://i56.tinypic.com/xeig7d.jpg\">
cheers. -
Superbugs:
Easier to do this question using model method.On Mon, M read 52 pages of a book. On Tues, he read 2/5 of the remaining pages. If he still had 1/3 of the book left to be read, how many pages were there in the book?
52 + XX ( read) + XXX( unread) = book
XXX ( unread) = 1/3 of book
2/3 of book = XXXXXX
therefore 52 + XX = XXXXXX
4X = 52
X= 13
Total pages in the book = 52 + 5X = 52 + 5(13) = 117 -
I still don’t get yours - Mathizzzfun!
However my DD can solve it easily so I rest my case!
Tks to all! -
pixiedust:
Ah, yes! I managed to get the correct answer, thanks piggylalala!
You're welcome
All the best for the PSLE next year. -
Hi,
was lost in dealing fractions / %. Pls help on the following qs:
1. At a toy fair 40% of those present were boys . 8/15 of the remainder were girls & the rest were adults. There were 480 more boys than adults. How many more children than adults were there at the toy fair?
2. Last mth, David use $840 of his salary to buy a laptop. He spent 1/8 of the remaining salary on rent, $400 on food & saved the rest. The amount that he spent on food was $20 less than that spent on rent.
a. What was his salary?
b. What % of his salary did he save?
3. Larry spent $60 less than 5/8 of his money on a MP3 player & $25 more than 7/9 of his remaining money on assessment books. After buying the assessement books, he still had $10 left.
a. How much money was left after Larry bought the MP3 player but before he bought the assessment books?
b. How much money did Larry have at first?
TIA -
Need help on this question!
There are 60% as many blueberry muffins as banana muffins and 20% more chocolate muffins than the blueberry muffins. What is the ratio of the number of banana muffins to the number of chocolate muffins? -
Superbugs:
HiNeed help on this question!
There are 60% as many blueberry muffins as banana muffins and 20% more chocolate muffins than the blueberry muffins. What is the ratio of the number of banana muffins to the number of chocolate muffins?
Blueberry : Banana = 60 : 100 = 3:5 -- (1)
Blueberry : Chocolate = 100 : 120 = 5:6 -- (2)
(1)x5, (2) x 3
Blueberry : Banana: Chocolate = 15 : 25 : 18
cheers. -
jtparent:
HiHi,
was lost in dealing fractions / %. Pls help on the following qs:
1. At a toy fair 40% of those present were boys . 8/15 of the remainder were girls & the rest were adults. There were 480 more boys than adults. How many more children than adults were there at the toy fair?
TIA
1. Boys = 40%, Girls + Adults = 60%
Girls = 8/15 x 60% = 32%, Adults = 60% - 32% = 28%
480 more boys than adults, so 40$ - 28% = 12% = 480, 1% = 40
Total children = 100% - 28% = 72%
72% - 28% = 44% = 44 x 40 = 1760
there were 1760 more children than adults.
cheers.
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